Suspend and resume in a time shared coprocessor

ABSTRACT

Multiple clients may attempt to utilize a coprocessor engine within a coprocessor simultaneously. However, each engine may accomplish the particular function for which it is designed for one client at a time. Therefore, to transition from performing coprocessor engine operations between clients, the coprocessor engine may be suspended from performing operations for a first client so that it may begin performing operations for a second client. Prior to such transition, the coprocessor engine saves metadata about its operation state at the time of the suspend. At a subsequent time, when operations for the first client are to resume, the operating state of the coprocessor engine is determined utilizing the metadata and operations for the first client resume.

FIELD OF THE INVENTION

Embodiments of the invention generally relate to computer systems andmore particularly to managing a suspend and subsequent resume offunctionality of a timeshared coprocessor in a computing systemincluding a processor and the coprocessor that share system memory.

DESCRIPTION OF THE RELATED ART

Heterogeneous computing systems combine different types of computeelements that share memory. A specific class of heterogeneous systemspairs traditional general-purpose processing cores and coprocessors.While this arrangement enables significant gains in applicationperformance, device driver overheads and operating system code pathoverheads can become prohibitive.

Some coprocessors are able to service numerous clients (e.g., softwareapplications, end users, partitions, or the like) and may be referred toas timeshared coprocessors. With the increasing number of clients thatthese coprocessors may service, efficiently managing the functionalityof such coprocessors is increasingly difficult.

SUMMARY

In an embodiment of the present invention, a computer system includes asystem memory shared by a processor and a coprocessor. The system memoryincludes a shared portion accessible by the coprocessor and theprocessor, a first client and a second client. The coprocessor includesa compression and decompression engine accessed by the first clientbeing executed by the processor and a second client being executed bythe processor and a suspend and resume manager that arbitrates firstclient and second client access to the compression and decompressionengine and saves coprocessor state metadata describing the contents ofthe compression and decompression engine to the system memory whensuspending first client access and allowing second client access to thecompression and decompression engine.

In another embodiment, a method of arbitrating first client and secondclient access to a compression and decompression engine within acoprocessor and saving coprocessor state metadata describing thecontents of the compression and decompression engine to system memoryconnected to the coprocessor and to a processor when suspending firstclient access and allowing second client access to the compression anddecompression engine includes retaining a copy of data currently withina history first-in-first-out (FIFO) buffer within system memory,suspending compression operations of the compression and decompressionengine by stopping data from entering the history FIFO buffer, upon thesuspend of compression operations, clearing contents of the historyFIFO, and writing a target empty bit count (TEBC) to system memory, theTEBC indicating the quantity of padding bits in the most recentcompressed output from the compression and decompression engine.

In yet another embodiment a method of arbitrating first client andsecond client access to a compression and decompression engine within acoprocessor and saving coprocessor state metadata describing thecontents of the compression and decompression engine to system memoryconnected to the coprocessor and to a processor when suspending firstclient access and allowing second client access to the compression anddecompression engine includes retaining a copy of a data decompressiontable utilized to decompress data within a history first-in-first-out(FIFO) buffer to system memory, suspending decompression operations ofthe compression and decompression engine by stemming data from enteringthe history FIFO buffer, upon the suspend of decompression operations,clearing contents of the history FIFO buffer and clearing contents ofthe decompression table, and writing a source unprocessed bit count(SUBC) and writing a source final block type (SFBT) to system memory,the SUBC indicating the amount of compressed data ingested by thecompression and decompression engine that was not decompressed, and theSFBT indicating a type of block that was being decoded upon thesuspending first client access to the compression and decompressionengine.

These and other embodiments, features, aspects, and advantages willbecome better understood with reference to the following description,appended claims, and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a high-level block diagram of an exemplary computersystem for implementing various embodiments of the invention.

FIG. 2 illustrates a block diagram of an exemplary computer systemincluding a processor and coprocessor for implementing variousembodiments of the invention.

FIG. 3 illustrates a block diagram of an exemplary compression systemwithin a coprocessor.

FIG. 4 illustrates a block diagram of an exemplary decompression systemwithin a coprocessor.

FIG. 5 illustrates an exemplary method of suspending compressionfunctions in a coprocessor, according to various embodiments of thepresent invention.

FIG. 6 illustrates an exemplary method of resuming compression functionsin a coprocessor, according to various embodiments of the presentinvention.

FIG. 7 illustrates an exemplary method of suspending decompressionfunctions in a coprocessor, according to various embodiments of thepresent invention.

FIG. 8 illustrates an exemplary method of resuming decompressionfunctions in a coprocessor, according to various embodiments of thepresent invention.

FIG. 9 illustrates an exemplary input buffer utilized in compressionand/or decompression functions within a coprocessor, according tovarious embodiments of the present invention.

FIG. 10 illustrates an exemplary method of setting a suspend thresholdvalue used to efficiently suspend compression or decompression functionsof a coprocessor, according to various embodiments of the presentinvention.

FIG. 11 depicts a cloud computing node according to an embodiment of thepresent invention.

FIG. 12 depicts a cloud computing environment according to an embodimentof the present invention.

FIG. 13 depicts abstraction model layers according to an embodiment ofthe present invention.

DETAILED DESCRIPTION

Embodiments related to arbitrating access between multiple clientsattempting to utilize a coprocessor engine within a coprocessorsimultaneously. Since each engine may accomplish the particular functionfor which it is designed for one client at a time, the coprocessorengine transitions from performing coprocessor engine operations betweenclients by suspending operations for a first client so that it may beginperforming operations for a second client. Prior to such transition, thecoprocessor engine saves metadata about its operation state at the timeof the suspend. At a subsequent time, when operations for the firstclient are to resume, the operating state of the coprocessor engine isdetermined utilizing the metadata and operations for the first clientresume.

Referring to the Drawings, wherein like numbers denote like partsthroughout the several views, FIG. 1 depicts a high-level block diagramrepresentation of a computer 100-A connected to another computer 100-Bvia a network 130, according to an embodiment of the present invention.The term “computer” is used herein for convenience only, and in variousembodiments is a more general data handling system, such as a mobilephone, tablet, server computer, etc. The mechanisms and apparatus ofembodiments of the present invention apply equally to any appropriatedata handling system. Further, recitations of computer 100 genericallyrefer to a computer and specific recitation of computer 100-A, 100-B,indicate specific computer 100 instances.

The major components of the computer 100 may comprise one or moreprocessors 101, a system memory 102, a terminal interface 111, a storageinterface 112, an I/O (Input/Output) device interface 113, and a networkinterface 114, all of which are communicatively coupled, directly orindirectly, for inter-component communication via a memory bus 103, anI/O bus 104, and an I/O bus interface unit 105. The computer 100contains one or more general-purpose programmable central processingunits (CPUs) 101A, 101B, 101C, and 101D, herein generically referred toas processor 101. In an embodiment, the computer 100 contains multipleprocessors 101 typical of a relatively large system; however, in anotherembodiment the computer 100 may alternatively be a single processor 101system. Each processor 101 executes instructions stored in the systemmemory 102 and may comprise one or more levels of on-board cache. Thecomputer 100-A further includes a coprocessor as is further describedherein. Generally, the coprocessor also executes instructions stored inthe system memory 102 and may comprise one or more levels of on-boardcache. The coprocessor generally allows the processor 101 to offload theexecution of instructions stored in the system memory 102 to thecoprocessor allowing the processor 101 to execute other instructionsstored in the system memory 102 or upon data that was previouslyexecuted by the coprocessor or upon data that will be subsequentlyexecuted by the coprocessor. This offloading to the coprocessorgenerally allows for accelerated execution of particular instructionsstored in the system memory 102. As such, the coprocessor may also bereferred to as an accelerator, acceleration unit, or the like.

In an embodiment, the system memory 102 may comprise a random-accesssemiconductor memory, storage device, or storage medium for storing orencoding data and programs. In another embodiment, the system memory 102represents the entire virtual memory of the computer 100, and may alsoinclude the virtual memory of other computer systems coupled to thecomputer 100 or connected via the network 130. The system memory 102 isconceptually a single monolithic entity, but in other embodiments thesystem memory 102 is a more complex arrangement, such as a hierarchy ofcaches and other memory devices. For example, memory 102 may exist inmultiple levels of caches, and these caches may be further divided byfunction, so that one cache holds instructions while another holdsnon-instruction data, which is used by the processor 101 and/orcoprocessors. Memory may be further distributed and associated withdifferent processors 101 or sets of processors 101, as is known in anyof various so-called non-uniform memory access (NUMA) computerarchitectures.

The system memory 102 stores or encodes an operating system 150, anapplication 160, and/or other program instructions. Although theoperating system 150, application 160, etc. are illustrated as beingcontained within the memory 102 in the computer 100, in otherembodiments some or all of them may be on different computer systems andmay be accessed remotely, e.g., via the network 130. The computer 100may use virtual addressing mechanisms that allow the programs of thecomputer 100 to behave as if they only have access to a large, singlestorage entity instead of access to multiple, smaller storage entities.Thus, while operating system 150, application 160, or other programinstructions are illustrated as being contained within the system memory102, these elements are not necessarily all completely contained in thesame storage device at the same time. Further, although operating system150, application 160, other program instructions, etc. are illustratedas being separate entities, in other embodiments some of them, portionsof some of them, or all of them may be packaged together.

In an embodiment, operating system 150, application 160, and/or otherprogram instructions comprise instructions or statements that execute onthe processor 101 and/or the coprocessor or instructions or statementsthat are interpreted by instructions or statements that execute on theprocessor 101 and/or the coprocessor, to carry out the functions asfurther described below. When such program instructions are able to berun by the processor 101 or the coprocessor, such computer 100 becomes aparticular machine configured to carry out such instructions.

One or more processors 101 may function as a general-purposeprogrammable graphics processor unit (GPU) that builds images (e.g. aGUI) for output to a display. The GPU, working in conjunction with oneor more applications 160, determines how to manipulate pixels on e.g.display, touch screen, etc. to create a display image or user interface.Ultimately, the image (e.g. GUI, etc.) is displayed to a user via a userI/O device 121. The processor 101 and GPU may be discrete components ormay be integrated into a single component.

The memory bus 103 provides a data communication path for transferringdata among the processor 101, the system memory 102, and the I/O businterface unit 105. The I/O bus interface unit 105 is further coupled tothe system I/O bus 104 for transferring data to and from the various I/Ounits. The I/O bus interface unit 105 communicates with multiple I/Ointerface units 111, 112, 113, and 114, which are also known as I/Oprocessors (IOPs) or I/O adapters (IOAs), through the system I/O bus104. The I/O interface units support communication with a variety ofstorage and I/O devices. For example, the terminal interface unit 111supports the attachment of one or more user I/O devices 121, which maycomprise user output devices (such as a video display device, speaker,and/or television set) and user input devices (such as a keyboard,mouse, keypad, touchpad, trackball, buttons, light pen, or otherpointing device). A user may manipulate the user input devices using auser interface, in order to provide input data and commands to the userI/O device 121 and the computer 100, and may receive output data via theuser output devices. For example, a user interface may be presented viathe user I/O device 121, such as displayed on a display device, playedvia a speaker, or printed via a printer. The user interface may be auser interface that provides content to a user visually (e.g. via ascreen), audibly (e.g. via a speaker), and/or via touch (e.g.vibrations, etc.). In some embodiments, the computer 100 itself acts asthe user interface as the user may move the computer 100 in ways tointeract with, input, or manipulate computer application 160 data,function, etc.

The storage interface unit 112 supports the attachment of one or morelocal disk drives or secondary storage devices 125. In an embodiment,the secondary storage devices 125 are rotating magnetic disk drivestorage devices, but in other embodiments they are arrays of disk drivesconfigured to appear as a single large storage device to a hostcomputer, or any other type of storage device. The contents of thesystem memory 102, or any portion thereof, may be stored to andretrieved from the secondary storage devices 125, as needed. The localsecondary storage devices 125 have a slower access time than does thememory 102, meaning that the time needed to read and/or write datafrom/to the memory 102 is less than the time needed to read and/or writedata from/to for the local secondary storage devices 125.

The I/O device interface 113 provides an interface to any of variousother input/output devices or devices of other types, such as printersor fax machines. The network adapter 114 provides one or morecommunications paths from the computer 100 to other data handlingdevices such as numerous other computers; such paths may comprise, e.g.,one or more networks 130. Although the memory bus 103 is shown in FIG. 2as a relatively simple, single bus structure providing a directcommunication path among the processors 101, the system memory 102, andthe I/O bus interface 105, in fact the memory bus 103 may comprisemultiple different buses or communication paths, which may be arrangedin any of various forms, such as point-to-point links in hierarchical,star or web configurations, multiple hierarchical buses, parallel andredundant paths, or any other appropriate type of configuration.Furthermore, while the I/O bus interface 105 and the I/O bus 104 areshown as single respective units, the computer 100 may, in fact, containmultiple I/O bus interface units 105 and/or multiple I/O buses 104.While multiple I/O interface units are shown, which separate the systemI/O bus 104 from various communications paths running to the various I/Odevices, in other embodiments some or all of the I/O devices areconnected directly to one or more system I/O buses.

I/O interface 113 may contain electronic components and logic to adaptor convert data of one protocol on I/O bus 104 to another protocol onanother bus. Therefore, I/O interface 113 may connect a wide variety ofdevices to computer 100 and to each other such as, but not limited to,tape drives, optical drives, printers, disk controllers, other busadapters, PCI adapters, PCIe adapters, NVLink adapters, workstationsusing one or more protocols including, but not limited to, Token Ring,Gigabyte Ethernet, Ethernet, Fibre Channel, SSA, Fiber ChannelArbitrated Loop (FCAL), Serial SCSI, Ultra3 SCSI, Infiniband, FDDI, ATM,1394, ESCON, wireless relays, Twinax, LAN connections, WAN connections,high performance graphics, etc.

Though shown as distinct entities, the multiple I/O interface units 111,112, 113, and 114 or the functionality of the I/O interface units 111,112, 113, and 114 may be integrated into a similar device.

In various embodiments, the computer 100 is a multi-user mainframecomputer system, a single-user system, a server computer, storagesystem, or similar device that has little or no direct user interface,but receives requests from other computer systems (clients). In otherembodiments, the computer 100 is implemented as a desktop computer,portable computer, laptop or notebook computer, tablet computer, pocketcomputer, telephone, smart phone, pager, automobile, teleconferencingsystem, appliance, or any other appropriate type of electronic device.

The network 130 may be any suitable network or combination of networksand may support any appropriate protocol suitable for communication ofdata and/or code to/from the computer 100A and at least the computer100B. In various embodiments, the network 130 may represent a datahandling device or a combination of data handling devices, eitherconnected directly or indirectly to the computer 100. In anotherembodiment, the network 130 may support wireless communications. Inanother embodiment, the network 130 may support hard-wiredcommunications, such as a telephone line or cable. In anotherembodiment, the network 130 may be the Internet and may support IP(Internet Protocol). In another embodiment, the network 130 isimplemented as a local area network (LAN) or a wide area network (WAN).In another embodiment, the network 130 is implemented as a hotspotservice provider network. In another embodiment, the network 130 isimplemented an intranet. In another embodiment, the network 130 isimplemented as any appropriate cellular data network, cell-based radionetwork technology, or wireless network. In another embodiment, thenetwork 130 is implemented as any suitable network or combination ofnetworks. Although one network 130 is shown, in other embodiments anynumber of networks (of the same or different types) may be present.

FIG. 1 is intended to depict the representative major components of thecomputer 100. But, individual components may have greater complexitythan represented in FIG. 1, components other than or in addition tothose shown in FIG. 1 may be present, and the number, type, andconfiguration of such components may vary. Several particular examplesof such additional complexity or additional variations are disclosedherein; these are by way of example only and are not necessarily theonly such variations. The various program instructions implementing e.g.upon computer system 100 according to various embodiments of theinvention may be implemented in a number of manners, including usingvarious computer applications, routines, components, programs, objects,modules, data structures, etc.

FIG. 2 illustrates a block diagram of an exemplary computer system 100including a processor and coprocessor for implementing variousembodiments of the invention. As depicted, the computer 100 furtherincludes a coprocessor 300 connected to processor 101 and system memory102 via memory bus 103 or via I/O bus 104. The coprocessor 300 executesinstructions stored in the system memory 102 and may comprise one ormore levels local memory such as on-board cache.

The coprocessor 300 allows the processor 101 to offload the execution ofinstructions stored in the system memory 102 to the coprocessor allowingthe processor 101 to execute other instructions stored in the systemmemory 102 or upon data that was previously executed by the coprocessoror upon data that will be subsequently executed by the coprocessor. Forexample, the coprocessor 300 may execute specific assigned instructionsstored in system memory 102 to accomplish a designated task so thatprocessor 101 need not execute those instructions, freeing up theprocessor 101 to accomplish other tasks. In another example, thecoprocessor 300 may execute portions of instructions stored in systemmemory 102 and the processor 101 may execute other portions of thoseinstructions to speed up the overall processing of that instruction set.This offloading to the coprocessor 300 generally allows for acceleratedexecution of particular instructions stored in the system memory 102.The coprocessor 300 may also be referred to as an accelerator,acceleration unit, or the like.

The coprocessor 300 may be located on the same system board, motherboard, printed circuit board, etc. as the processor 101. For example,the coprocessor 300 may be connected to the processor 101 and systemmemory 102 via a system board bus, mother board bus, printed circuitboard bus, such as memory bus 103. Alternatively, the coprocessor 300may be located on an expansion card, adapter card, or the like. Forexample, the coprocessor 300 may be connected to the processor 101 andsystem memory 102 via a connector (e.g., I/O bus interface 105)connecting the system board (comprising the processor 101 and systemmemory 102) and the adapter card (comprising the coprocessor 300). Inother words, the coprocessor 300 may be located within interface 200which generally refers to terminal interface 111, storage interface 112,I/O device interface 113, or network interface 114.

Processor 101 may further include a data mover 224 that controls adiscrete memory portion of system memory 102. If coherent computer 201includes multiple discrete memory portions, processor 101 may includemultiple data movers 224 each associated with a respective discretememory portion of system memory 102.

Coprocessor 300 may include one or more coprocessor engines that carryout computational tasks. The term “engine” is defined herein as one ormore tangible hardware devices, such as a circuit, a buffer, register,etc. that accomplish a particular coprocessor 300 function. Eachcoprocessor engine may comprise solely the one or more tangible hardwaredevices or the compressor engine may further comprise programinstructions utilized, called, executed, etc. by the one or moretangible hardware device to become a particular machine configured tocarry out the particular function. For example, coprocessor 300 mayinclude one or more compression/decompression engines 320, one or moreencryption/decryption engines 330, and one or more deflatecompression/decompression engines 340. Note, the term “deflate” isherein utilized to refer to the compressed data format specificationRFC1951, informally referred to as zip, gzip, or deflate.

Multiple clients, such as multiple applications 160, partitions, etc.may attempt to utilize each coprocessor engine simultaneously. However,each engine may accomplish the particular function for which it isdesigned for one client at a time. For example, a first application 160may be utilizing deflate compression/decompression engine 340 tocompress a first file. During the compression operation of the firstfile, a second application 160 may attempt to utilizecompression/decompression engine 340 to compress a second file. It maybe determined that the second file has a higher priority than the firstfile. Therefore, to transition from operating upon the first file tosecond file, the compression/decompression engine 340 may be suspendedfrom compressing the first file so that it may begin compressing thesecond file. Prior to such transition, the compression/decompressionengine 340 saves metadata about its operation state at the time of thesuspend. At a subsequent time, the deflate compression/decompressionengine 340 may resume compression operations upon the first file. Toefficiently resume such operations, the operating state of thecompression/decompression engine 340 is determined utilizing themetadata and compression of the first file resumes.

Coprocessor 300 may further include a data mover 310 and processorinterface 360. The data mover 310 reads and writes data and status onbehalf of the engines as directed by the Coprocessor Request Block (CRB)206. The data mover 310 may include a data channel per each engine. Forexample, if the coprocessor 300 includes five engines, the coprocessor300 includes channel 350 associated with data movement to and fromengine 320A, channel 351 associated with data movement to and fromengine 320B, channel 352 associated with data movement to and fromengine 330A, channel 353 associated with data movement to and fromengine 330B, and channel 354 associated with data movement to and fromengine 340. The CRB 206 may include two queue positions per channel: onefor currently executing on the engine and one for awaiting execution onthe engine.

The processor interface 360 interfaces to bus 103 or bus 104, dependingupon the location of coprocessor 300, and to data mover 310. Theprocessor interface 360 may include a common queue 362. The common queue360 may include a User Mode Access Control (UMAC) coprocessor invocationblock 364, a data mover interface 366, and a random number generator370.

The UMAC 364 fetches CRB 206 from in-memory work queues and dispatchesthem to data mover 310. The data mover interface 366 adapts the datamover 310 and RNG 370 to common queue 362. Random number generator 370is a true random number generator.

To fetch data on behalf of an engine, the data mover 310 makes readrequests for cache lines to the processor interface 360 by writingrequest information (address, size, and tag) in the common queue 362 inthe processor interface 360. This assigns a particular read machine tohandle the request. If translation is required on an address, the ERAT368 is accessed to determine the translation exists. If the translationdoes not exist, a checkout request is made and a either a real addressor a fault is returned. Assuming that a real address is returned, thereal address is substituted for the effective address in the request.The processor interface 360 signals the data mover 310 that read data isavailable, passing the number of the read machine that handled therequest to the data mover 310. The data mover 310 uses the machinenumber to access the common queue 362, retrieving the information itwrote there when making the request.

The data mover 310 uses a tag to identify the data returned and moves itto the corresponding ingress buffer 344 entry. In a sequence of datamover 310 read requests, the lines may come back in any order and thetag allows the data mover 310 to put the lines back in order in itsingress buffer 344 before forwarding it on to an appropriate engine.

Upon being signaled to start, the engine commences making requests forCoprocessor Parameter Block (CPB) data one word at a time. The engineaccepts each word requested and the appropriate channel transfers eachword from its ingress buffers 344 to the engine. The data transferred tothe engine may be transferred in order. The channel aligns all ingress344 data as required by the engine. Such requirements may differ fromone engine type to another. The engine knows how many CPB words comprisethe operation and signals to the channel when a request is the lastword. After receiving all CPB, the engine makes requests for sourcedata. The channel transfers each word of source data to the engine,accompanying each with an acknowledgement until the last word istransferred together with a “last data” indication. In embodiments, onlythe CPB 206 data may be needed as inputs for the engine operation. Inother embodiments, input buffer 202 data as specified by one or moredata descriptors present in the CPB 206 may be needed as inputs for theengine operations. The one or more data descriptors present in the CRB206 may effectively point to other data descriptors within input buffer202 to gather the source data for the engine operation.

To return data on behalf of an engine, the output data from the engineis written to a location in output buffer 204 as specified by one ormore data descriptors within CRB 206. When an output word is available,the engine asserts an output request to the channel and the channelaligns the data within cache lines according to the starting address ofthe destination. The channel transfers the word to an egress buffer 342from where it is transferred to write buffers in the common queue 362.When a line of data has been written into the common queue 362, thechannel signals to the processor interface 360 that a line is availableto be written to storage, provides an address for the data to the ERAT368, and selects a free data mover 310 write machine to perform thewrite. If translation is required on an address, the ERAT 368 isaccessed to determine the translation exists. If the translation doesnot exist, a checkout request is made and either a real address or afault is returned. Assuming that an RA is returned, the real address issubstituted for the effective address in the request. The processorinterface 360 enqueues the request in common queue 362 and the datamover 310 write machine then performs the bus tasks necessary toproperly store the line. This process continues until the engine hasindicated that the last word of target data has been transferred.

In particular embodiments, system memory 102 may further include InputCoprocessor Parameter Block (CPBin) 208 and Output Coprocessor ParameterBlock (CPBout) 210. CPBin 208 and CPBout 210 may be, for instance,utilized when the engine operations are suspended and resumed. Forexample, engine state metadata is written to CPBout 210 for restoringthe engine state when resuming the compression job.

FIG. 3 illustrates a block diagram of an exemplary compression system400 within coprocessor 300. More particularly, exemplary compressionsystem 400 may be located within deflate compression decompressionengine 340. Compression system 400 may include the input buffer 202,output buffer 204, LZ encoder 404, Huffman decoder 405, History FIFO406, Hash Device 408, Hash Dictionary 410, and Next Address Counter 412.History FIFO 406 and Hash Dictionary 410, also referred to as a HashTable, are located within the local memory of coprocessor 300. Forexample, History FIFO 406 and Hash Dictionary 410 are located withincoprocessor 300 static random-access memory (SRAM), cache, etc.

The LZ encoder 404, Huffman decoder 405, History FIFO 406, Hash Device408, Hash Dictionary 410, and Next Address Counter 412 are generallyknown hardware elements within deflate compression and decompressionsystems, such as a zip compression and decompression system. Asdepicted, compression system 400 may further include a suspend andresume manager 430 to control the suspend and resumption of thecompression system 400. Suspend and resume manager 430 includes atangible portion(s) of coprocessor 300 (e.g., circuits, registers,storage, etc.) along with program instructions utilized, called,executed, etc. by those portion(s) of coprocessor 300 to become aparticular machine configured to carry out functions of the programinstructions. The suspend and resume manager 430 generally arbitratescompeting client access to particular coprocessor 300 engines. Suspendand resume manager 430 may allow or not allow access to particularengines of the coprocessor by e.g., stopping data flow into a particularengine, determining that data flow into a particular engine has ceasedand the engine should be transferred to another client, etc. Whensuspend and resume manager 430 determines that access to a first clientshould cease it generally suspends engine operations associated with thefirst client so that the engine operations may be utilized by a secondclient. When suspend and resume manager 430 determines that access tothe first client should be again allowed after the suspend it generallyresumes engine operations associated with the first client so that theengine operations may given back to the first client.

The History FIFO 406 may be associated with compression and/ordecompression functions. For example, a single history FIFO 406 may beutilized by both compression and decompression operations.Alternatively, a first history FIFO 406 may be utilized by compressionoperations and a second history FIFO 406 may be utilized bydecompression operations.

In some embodiments, suspend and resume manager 430 is located withinprocessor 101 and therefore includes a tangible portion(s) of processor101 (e.g., circuits, registers, storage, etc.) along with programinstructions utilized, called, executed, etc. by those portion(s) ofprocessor 101 to become a particular machine configured to carry outfunctions of the program instructions. In other embodiments, firstportions of suspend and resume manager 430 may be located withincoprocessor 300 and second portions of suspend and resume manager 430may be located within processor 101.

In an exemplary compression operation, a new input word arrives frominput buffer 202. A copy of the raw (i.e., non-compressed) most recentinput words within the FIFO buffer 406 are retained in the input buffer202. The new input word is written to the history FIFO buffer 406 at asequential FIFO address, written to LZ encoder 404, and written to hashdevice 408 to obtain a hash address. Counter 412 writes the assignedFIFO address to a Hash Dictionary 410 entry, which is also referred toas a Hash Table. Counter 412 may then be incremented to determine a nextsequential FIFO address to prepare for a subsequent input word.

A hash value at the hash address is read from the Hash Dictionary 410.The hash value is used as a FIFO address and an associated phrase isread from the history FIFO buffer 406 by LZ encoder 404. The LZ encoder404 compares the associated phrase read from the history FIFO buffer 406to the new input word. If the phrase read from the history FIFO buffer406 and the new input word are equal, the LZ outputs the distance fromthe new input word to the phrase read from the history FIFO buffer 406to form a pointer that replaces duplicate phrases. The output from theLZ encoder 404 may be further compressed by Huffman Encoder 405 as isknown in the art. The compressed output from the encoder is written tooutput buffer 204.

The compression system 400 does not require all data to be present ininput buffer 202 before a compress begins. Source data may becomeavailable piecemeal, for example, when reading as small chunks fromstorage device 125 or network 130, because the source buffer 202 is notbig enough to contain an entire input. The suspend & resume manager 430generally manages the starting and stopping of execution of thecompression system 400. For example, when the source buffer 202 isdepleted, the suspend & resume manager 430 suspends execution and writesmetadata about the internal state of compression system 400 to CPBout210. When the suspend & resume manager 430 resumes the execution of thecompression system 400, operations resume from where there weresuspended by reading the state metadata from CPBin 208.

Compression system 400 may also be suspended when it reaches a systemdetermined job length limit. For example, a job length limit may bespecified in configuration register 432 and utilized for fair schedulingof multiple compression jobs from competing users and for high priorityjobs to preempt low priority jobs. For example, an interrupt handlersoftware routine needing engine 340 may preempt a user mode application160 running a long compression operation.

Suspend & resume manager 430 suspends compression system 400 by stoppingnew input data words from streaming into compression system 400 frominput buffer 202. When compression system 400 is suspended, the bulk ofthe state of the compression system 400 is contained in history FIFObuffer 406 and the Hash Table. To reduce the amount of data saved tosystem memory 102 when saving the state of compression system 400 uponsuspend, metadata describing the state of compression system 400 issaved to CPBout 210, as opposed to the entire contents of the historyFIFO buffer 406. At the time of resuming compression system 400, suspend& resume manager 430 utilizes the metadata to recreate the history FIFObuffer 406 and the Hash Table so that compression operations may beresumed from where there were suspended.

Upon the suspend, suspend & resume manager 430 clears the contents ofhistory FIFO buffer 406 and saves a Target Empty Bit Count (TEBC) toCPBout 210. TEBC is the metadata describing the state of compressionsystem 400 upon suspend and identifies the quantity of padding bits inthe most recent byte of the compression system 400 output. Padding bitsare added to new input words to make the new input words a length equalto that stored within history FIFO buffer 406. In other words, paddingbits are filler bits. When compression operations resume, the TEBC valueis read by the client associated with the previous suspend to alignnewly compressed output from the compression system 400 to the mostrecent byte of the compression system 400 output prior to the suspend.

Suspend & resume manager 430 resumes compression system 400 by restoringthe contents of history FIFO buffer 406 and the Hash Table. To restorethe contents of the history FIFO buffer 406 the copy of the most recentinput words that were previously within the history FIFO buffer 406 areread from the input buffer 202. For example, an input buffer 202 pointermay be rewound by the size of the history FIFO buffer 406 and the dataidentified by the rewound pointer may be read from input buffer 202 intohistory FIFO buffer 406. The Hash Table is restored by recomputing hashdevice 408 hash functions and rewriting the Hash Table as is generallyknown in the art. During the restoration of the history FIFO buffer 406and the Hash Table, no compressed output is processed by compressionsystem 400 as the internal history of the compression system 400 isbeing restored to arrive at the similar state at the time of suspend.The TEBC value is read from CPBin 208 and newly compressed output fromthe compression system 400 is aligned to the most recent byte of thecompression system 400 output prior to the suspend and the compressionsystem 400 suspend.

The previous and new compressed output may be aligned by the client(i.e. the client associated with the previous suspend) reading the TEBCvalue to determine that the last byte of output had the specifiedquantity of filler bits. The associated client can align the previousand new compressed output by various techniques. First, the associatedclient may add a number of padding bits to the new compressed output toalign the new output to the previous byte's boundary. Padding bits maybe byte aligning control characters as defined by the deflate method. Inanother technique, the associated client may shift the new output by theTEBC value to overwrite the previous output's padding bits.

FIG. 4 illustrates a block diagram of an exemplary decompression system500 within a coprocessor. More particularly, exemplary decompressionsystem 500 may be located within deflate compression decompressionengine 340. Decompression system 500 may include the input buffer 202,output buffer 204, Huffman decoder 504, LZ decoder 505, History FIFO406, Huffman Table Decoder 506, Huffman Table 508, and Next AddressCounter 412. History FIFO 406 and Huffman Table 508 are located withinthe local memory of coprocessor 300. For example, History FIFO 406 andHuffman Table 508 are located within coprocessor 300 SRAM, cache, etc.

Huffman decoder 504, LZ decoder 505, History FIFO 406, Huffman TableDecoder 506, Huffman Table 508, and Next Address Counter 412 aregenerally known hardware elements within deflate compression anddecompression systems. As depicted, decompression system 500 may furtherinclude a suspend and resume manager 430 to control the suspend andresumption of the decompression system 500. Suspend and resume manager430 may comprise program instructions utilized, called, executed, etc.by the coprocessor 300 to become a particular machine configured tocarry out functions of the program instructions.

In an exemplary decompression operation, compressed data arrives frominput buffer 202. The compressed data contains a dynamic Huffman Table508 and the table 508 is decoded and stored in the local memory ofcoprocessor 300. The compressed data is decoded by the Huffman Decoder504 and the LZ decoder 505 sequentially, as is known in the art. If a LZcoded sequence contains a pointer, such as a Length-Distance, pair, theassociated stored phrase is read from History FIFO 406. LZ literalphrases and LZ decoded phrases are assembled to reconstitute theuncompressed raw data which is written to the output buffer 204 and tothe History FIFO 406.

The suspend & resume manager 430 generally manages the starting andstopping of execution of the decompression system 500. For example, whenthe source buffer 202 is depleted, the suspend & resume manager 430suspends execution and writes metadata about the internal state ofdecompression system 500 to CPBout 210. When suspend & resume manager430 resumes the execution of the decompression system 500, operationsresume from where there were suspended by reading the state metadatafrom CPBin 208.

Suspend & resume manager 430 suspends decompression system 500 bystopping new compressed data words from streaming into decompressionsystem 500 from input buffer 202. When decompression system 500 issuspended, the bulk of the state of the decompression system 500 iscontained in history FIFO buffer 406 and the Huffman Table 508. Toreduce the amount of data saved to system memory 102 when saving thestate of decompression system 500 upon suspend, metadata describing thestate of decompression system 500 is saved to CPBout 210, as opposed tothe entire contents of the history FIFO buffer 406 and Huffman Table508. At the time of resuming decompression system 500, suspend & resumemanager 430 utilizes the metadata to recreate the history FIFO buffer406 and the Huffman Table 508 so that decompression operations may beresumed from where there were suspended.

Upon suspend, suspend & resume manager 430 clears the contents ofhistory FIFO buffer 406 and the Huffman Table 508 and writes the HuffmanTable 508 stored within the local memory of coprocessor 300 and thelength of the Huffman Table 508 to CPBout 210, writes a sourceunprocessed bit count (SUBC) to CPBout 210, and writes a source finalblock type (SFBT) to CPBout 210.

As suspend & resume manager 430 may suspend a decompression operationsat any point in the decompression operation, suspend & resume manager430 may continuously checkpoint the compressed input data stream frominput buffer 202 at predetermined intervals. The SUBC value indicatesthe location of the most recent checkpoint relative to the currentlocation at which the decompress operation is suspended. In other words,the SUBC value indicates the amount of compressed source data ingestedby the coprocessor 300 but was not decompressed. If for example, thesource data is cut short in the middle of the Huffman decode, the SUBCvalue indicates how many bits of compressed source data must beresubmitted upon resuming.

Suspend & resume manager 430 also writes to CPBout 210, the type ofblock that was being decoded when the suspend occurred as the SFBTvalue. As is known in the art, decompression operations may decompressthree different types of blocks: type 0, type 1, or type 2. As such, theSFBT value identifies the type of block was being decoded when thesuspend occurred as a type 0, type 1, or type 2 block.

Suspend & resume manager 430 resumes decompression system 500 byrestoring the contents of history FIFO buffer 406 and the Huffman Table508. The Huffman Table 508 is restored by reading the Huffman Table 508copy from system memory 102, decoding the read Huffman Table 508 withHuffman table decoder 506, if needed, and storing the recreated decodedHuffman Table 508 in the local memory of coprocessor 300.

To restore the input bits which the coprocessor 300 had dropped prior tosuspend, the client associated with the prior suspend rewinds the inputbuffer pointer by the SUBC amount and writes the associated data intothe appropriate decompression component (e.g., Huffman decoder 504, LZdecoder 505, etc.) so that coprocessor 300 may operate upon thosepreviously dropped bits. On the output side of the coprocessor 300decompression operations, the previously decompressed contents of thehistory FIFO buffer 406 that were dropped in association with thesuspend may be restored by the associated client (i.e., the clientassociated with the previous suspend) by reading/writing up to thehistory-FIFO-maximum number of bytes from the output buffer 204 tohistory the FIFO 406.

The contents of the history FIFO buffer 406 may be restored by theassociated client (i.e., the client associated with the previoussuspend) according to the SUBC value and the history FIFO 406 contentsare recreated by reading up to the history-FIFO-maximum number of bytesfrom input buffer 202 and writing them to history FIFO 406.

FIG. 5 illustrates an exemplary method 600 of suspending compressionfunctions in coprocessor 300, according to various embodiments of thepresent invention. Method 600 may be utilized, for example, by computer100, processor 101, coprocessor 300, suspend & resume manager 430, orother computing device, or a combination of such devices, to manage orcontrol the suspend of a compression function being executed uponcoprocessor 300. The suspend may be apart of a coprocessor 300arbitration scheme so that compression functions may be delivered tonumerous clients (i.e. different applications 160, different users,different partitions, etc.) in a time shared manner. For example, afirst application 160 may be utilizing deflate compression/decompressionengine 340 to compress a first file. During the compression operation ofthe first file, a second application 160 may attempt to utilizecompression/decompression engine 340 to compress a second file. Thesuspend & resume manager 430 may determine that the second file has ahigher priority than the first file. Therefore, to transition fromoperating upon the first file to second file, the suspend & resumemanager 430 suspends compression/decompression engine 340 fromcompressing the first file so that it may begin compressing the secondfile.

Prior to such transition, the compression/decompression engine 340 savesmetadata about its operation state at the time of the suspend. At asubsequent time, the compression/decompression engine 340 may resumecompression operations upon the first file. To efficiently resume suchoperations, the operating state of the compression/decompression engine340 is determined utilizing the metadata and compression of the firstfile resumes.

Method 600 begins at block 602 and continues by retaining a copy of thestreaming data currently in history FIFO 406 within system memory 102.For example as data streams into history FIFO 406 from input buffer 202a copy of the data is retained in system memory (i.e. within inputbuffer 202, another location of system memory 102, etc.). As the data iscompressed and delivered to output buffer 204 and new data enters thehistory FIFO 406 the retained copy of the data within system memory 102is updated. In other words, the content of the history FIFO 406 mirrorsthe retained data copy within system memory 102.

Method 600 may continue by suspending the compression operation (block606). For example, incoming streaming data into history FIFO 406 stops.The suspend of the incoming data may be stopped by e.g. suspend & resumemanager 430 by monitoring configuration register 432 to determinewhether a predetermined job length limit threshold is exceeded in orderto arbitrate the compression function between competing clients.Alternatively, the suspend operation may be suspended when the sourcebuffer 202 is depleted of incoming data.

Method 600 may continue by clearing the contents of the history FIFO(block 608). For example, the suspend & resume manager 430 may delete,drop, forget, rewrite, indicate as insignificant, destroy, or otherwisedispose of the contents of the history FIFO 406.

Method 600 may continue by writing metadata describing the internalstate of coprocessor 300 to system memory 102. For example, the suspend& resume manager 430 writes metadata describing the contents of thehistory FIFO 406 that were cleared or are to be cleared to CPBout 210.When compression operations resume the compression operations are ableto resume from where there were suspended by reading this metadata. In aparticular embodiment, the metadata is a TEBC value written to CPBout210 (block 612). TEBC indicates the number of padding bits in the mostrecent byte of the compressed output delivered to output buffer 204.Padding bits may have been added to new input data to make the new inputa length equal to that stored within history FIFO buffer 406. Whencompression operations resume, the TEBC value is read in order to alignnewly compressed output of the coprocessor 300 to the previous outputthe coprocessor 300 prior to the suspend. Method 600 ends at block 614.

FIG. 6 illustrates an exemplary method 650 of resuming compressionfunctions in coprocessor 300, according to various embodiments of thepresent invention. Method 650 may be utilized, for example, by computer100, processor 101, coprocessor 300, suspend & resume manager 430, orother computing device, or a combination of such devices, to manage orcontrol resuming of the compression function previously suspended uponcoprocessor 300. The resumption may be apart of a coprocessor 300arbitration scheme so that compression functions may be delivered to apreviously suspended client.

Method 650 begins at block 652 and may continue with determining thatcompression operation that was previously suspended should resume (block654). For example, suspend & resume manager 430 determines thatoperations should be given back to the application 160 associated withthe suspend and resumes the compression operation by restoring thecontents of history FIFO buffer 406 and the Hash Table referencing themetadata previously saved to system memory 102.

Method 650 may continue by rewinding a system memory 102 pointer by alength equivalent to the size of the history FIFO buffer 406 (block656). Method 650 may continue by restore the contents of the historyFIFO buffer 406 by loading the data identified by the rewound systemmemory 102 pointer into the history FIFO buffer 406 (block 660). In thisway, the contents of the history FIFO buffer 406 at the time ofcompression operation suspend are loaded back to the history FIFO buffer406 from system memory 102.

Method 650 may continue by recomputing Hash Functions of the Hash Device408 and rewriting the Hash Dictionary 410 (block 662). Techniques torecompute the hash device 408 hash functions and rewrite the HashDictionary 410 are generally known in the art.

Method 650 may continue by resuming the compression function with newlycompressed output aligned with compressed output prior to thecompression operation being suspended (block 664). For example, the TEBCvalue may be read from CPBin 208 and newly compressed output from thecompression system 400 is aligned to the most recent byte of thecompression system 400 output prior to the suspend and the compressionsystem 400 suspend. The previous and new compressed output may bealigned by the associated client (i.e. the client that requestedoperations of the previous suspend) reading the TEBC value to determinethat the last byte of output had the specified quantity of filler bits.The associated client can align the previous and new compressed outputby two techniques. First, the associated client may append a number ofpadding bits to the new compressed output to align the new output to theprevious byte's boundary. In another technique, the associated clientmay shift the new output by the TEBC value to overwrite the previousoutput's filler bits. Method 650 ends at block 666.

FIG. 7 illustrates an exemplary method 700 of suspending decompressionfunctions in coprocessor 300, according to various embodiments of thepresent invention. Method 700 may be utilized, for example, by computer100, processor 101, coprocessor 300, suspend & resume manager 430, orother computing device, or a combination of such devices, to manage orcontrol the suspend of a decompression function being executed uponcoprocessor 300. The suspend may be apart of a coprocessor 300arbitration scheme so that decompression functions may be delivered tonumerous clients (i.e. different applications 160, different users,different partitions, etc.) in a time shared manner. For example, afirst application 160 may be utilizing deflate compression/decompressionengine 340 to decompress a first file. During the decompressionoperation of the first file, a second application 160 may attempt toutilize compression/decompression engine 340 to decompress a secondfile. The suspend & resume manager 430 may determine that the secondfile has a higher priority than the first file. Therefore, to transitionfrom operating upon the first file to second file, the suspend & resumemanager 430 suspends compression/decompression engine 340 fromdecompressing the first file so that it may begin decompressing thesecond file. Prior to such transition, the compression/decompressionengine 340 saves metadata about its operation state at the time of thesuspend. At a subsequent time, the compression/decompression engine 340may resume decompression operations upon the first file. To efficientlyresume such operations, the operating state of thecompression/decompression engine 340 is determined utilizing themetadata and decompression of the first file resumes.

Method 700 begins at block 702 and continues by decompression operationsbeginning (block 704). For example, compressed data streams from inputbuffer 202 to be decompressed. Method 700 may continue with thedecompression table associated, embedded, etc. with the compressed datainput being decoded and saved in system memory 102 (block 706). Forexample, the Huffman Table 508 is decoded and saved in the local memoryof coprocessor 300 to be utilized in decompression operations. TheHuffman Table 508 is also decoded and saved in system memory 102 so thatit may be recalled, decoded, and/or utilized when decompression functionis resumed.

Method 700 may continue by suspending decompression operations (block708). In other words, the incoming compressed streaming data stops. Thesuspend of the compressed incoming data may be stopped by e.g. suspend &resume manager 430 by monitoring configuration register 432 to determinewhether a predetermined job length limit threshold is exceeded in orderto arbitrate the decompression function between competing clients.Alternatively, the suspend operation may be suspended when the sourcebuffer 202 is depleted of incoming compressed data.

Method 700 may continue by clearing the contents of the history FIFO 406(block 710). For example, the suspend & resume manager 430 may delete,drop, forget, rewrite, indicate as insignificant, destroy, or otherwisedispose of the contents of the history FIFO 406.

Method 700 may continue by writing metadata describing the internalstate of coprocessor 300 to system memory 102 (block 712). For example,the suspend & resume manager 430 writes metadata describing the contentsof the history FIFO 406 to CPBout 210. When decompression operationsresume the decompression operations are able to resume from where therewere suspended by utilizing metadata to align the new output to theprevious output.

In a particular embodiment, the metadata is a SUBC value written toCPBout 210 (block 714) and/or a SFBT value written to CPBout 210. Assuspend & resume manager 430 may suspend a decompression operations atany point in the decompression operation, suspend & resume manager 430may continuously checkpoint the compressed input data stream from inputbuffer 202 at predetermined intervals, lengths, etc. The SUBC valueindicates the location of the most recent checkpoint relative to thecurrent location at which the decompress operation is suspended. Inother words, the SUBC value indicates the amount of compressed sourcedata ingested by coprocessor 300 but was not decompressed. If forexample, the source data is cut short in the middle of the Huffman Table508 decode, the SUBC value indicates how many bits of compressed sourcedata must be resubmitted. The suspend & resume manager 430 can calculatethe resume address by subtracting the SPBC from the location of the mostrecent checkpoint.

Suspend & resume manager 430 may also write the SFBT value to CPBout 210(block 716). The SFBT indicates the type of block that was being decodedwhen the decompression suspend occurred. The SFBT value generallyidentifies the type of block was being decoded when the suspend occurredas a type 0, type 1, or type 2 block. Method 700 ends at block 718.

FIG. 8 illustrates an exemplary method 750 of resuming decompressionfunctions in coprocessor 300, according to various embodiments of thepresent invention. Method 750 may be utilized, for example, by computer100, processor 101, coprocessor 300, suspend & resume manager 430, orother computing device, or a combination of such devices, to manage orcontrol resuming of the decompression function previously suspended uponcoprocessor 300. The resumption may be apart of a coprocessor 300arbitration scheme so that decompression functions may be delivered to apreviously suspended client.

Method 750 begins at block 752 and continues when determining thatdecompression function shall resume (block 754). For example, suspend &resume manager 430 may determine that the decompression function of thecoprocessor 300 is not currently utilized and that a previouslysuspended decompression operation should be resumed.

Method 750 may continue by recreating the state of the coprocessor 300(block 756). For example, suspend & resume manager 430 determines thetype of block that was being operated upon at the time of the suspend byreading the SFBT value from CPBin 208 (block 758), determines the amountof compressed data previously ingested by coprocessor 300 but was notdecompressed by reading the SUBC value from CPBin 208 (block 760), andreads the copy of the Huffman Table 508 associated with the previouslyingested by coprocessor 300 from system memory 102 (block 762).

Method 750 may continue by restoring the decompression table and savingthe decompression table to the local memory of coprocessor 300. Forexample, suspend & resume manager 430 may restore the Huffman Table 508by reading the Huffman Table 508 copy from system memory 102, decodingthe read Huffman Table 508 with Huffman table decoder 506, if needed,and storing the decoded Huffman Table 508 in the local memory ofcoprocessor 300.

Method 750 may continue by rewinding the system memory 102 pointer by aquantity specified by the SUBC value (block 766). For example, theclient associated with the previous suspend rewinds the input buffer 202pointer according to the SUBC value to point to the compressed data wordwithin input buffer 202 that was previously ingested by coprocessor 300but was not decompressed. Method 750 may continue by reading thecompressed data as indicated by the system memory pointer into theappropriate decompression component, such as the Huffman decoder 504, LZdecoder 505, etc. (block 768). For example, the client associated withthe previous suspend loads the compressed data that was previouslyingested by coprocessor 300 but was not decompressed from input buffer202 by calling the data word identified by the pointer from input buffer202. The compressed data word that was located within history FIFO 406and dropped at the previous suspend, may be written back to history FIFO406 by writing up to the size of history FIFO 406 of the most recentdecompressed data from output buffer 204 that were associated with theoperations immediately preceding the suspend.

Method 750 may continue by resuming data decompression operations withthe new decompressed output aligned to the previous decompressed output(block 770). For example, the client associated with the previoussuspend aligns the new decompressed output with the previousdecompressed output by connecting, making congruent, making contiguousor otherwise associating to the new decompressed output with theprevious decompressed output. Method 750 ends at block 772.

FIG. 9 illustrates an exemplary input buffer 800 utilized in compressionand/or decompression functions within coprocessor 300, according tovarious embodiments of the present invention. Generally, input buffer800 may be a compression input buffer that may be accessed bycoprocessor 300 to compress data or a decompression input buffer thatmay be accessed by coprocessor 300 to decompress data. Input buffer 800includes a high priority buffer (HPB) portion 802 and a low prioritybuffer (LPB) portion 804. In embodiments, the HPB 802 is shorter,smaller, etc. relative to the LPB 804. HPB 802 is utilized byapplications 160 calling coprocessor 300 having short deadlines. Forexample, HPB 802 is utilized by an interrupt handler application 160. Insuch embodiments, LPB 804 is utilized by applications 160 that canoperate in a batch mode, where completion time is not critical.

In an embodiment, to increase overall system performance, the suspendand subsequent resumption of operations of a coprocessor 300 should beminimized as the processes to save or recall the state metadata of thecoprocessor 300 take computational time away from actual coprocessor 300(e.g., compression, decompression, etc.) operations.

To limit the instances of suspending and resuming of operations ofcoprocessor 300, a configuration register 432 may be utilized by thesuspend and resume manager 430. The configuration register 432 isgenerally located within the local memory of coprocessor 300 and is aspecific location whereby a suspend threshold value may be set. Thesuspend threshold value may be set to a high value or a low valuedepending upon the existence of applications 160 utilizing the HPB 802and or the LPB 804 For example, a low suspend threshold value may be setif the HBP 802 includes data to be operated upon by the coprocessor 300.A low suspend threshold value generally allows for more frequent suspendof operations of coprocessor 300. A high suspend threshold valuegenerally allows for less frequent suspend of operations of coprocessor300, relative to the low suspend threshold value.

FIG. 10 illustrates an exemplary method 850 of setting a suspendthreshold value used to efficiently suspend coprocessor functions,according to various embodiments of the present invention. Method 850may be utilized, for example, by computer 100, coprocessor 300, suspend& resume manager 430, or other computing device, or a combination ofsuch devices, to set a high or low suspend threshold value. The settingof the suspend threshold value may be apart of a coprocessor 300arbitration scheme so that coprocessor 300 function may be efficientlysuspended in association with a first client so that the function may beoffered or delivered to a second client.

Method 850 starts at block 852 and continues with determining if the HPB802 is empty (block 854). If the HPB 802 is empty no high priorityapplications 160 are requesting the utilization of coprocessor 300. Ifthe HBP 802 is not empty at least one high priority applications 160 arerequesting the utilization of coprocessor 300. If the HPB 802 is empty,a high suspend threshold value is set within configuration register 432(block 856). If the HPB 802 is not empty, a low suspend threshold valueis set within configuration register 432 (block 857). Therefore, forexample, if HPB 802 is empty, it is relatively more difficult forsuspend & resume manager 430 to suspend operations of the coprocessor300 so that function of the coprocessor 300 may be given to a competingclient. Method 850 ends at block 858.

FIG. 11 illustrates an exemplary method 870 of setting a suspendthreshold value used to efficiently suspend coprocessor 300 functions,according to various embodiments of the present invention. Method 870may be utilized, for example, by computer 100, coprocessor 300, suspend& resume manager 430, or other computing device, or a combination ofsuch devices, to set a high or low suspend threshold value. The settingof the suspend threshold value may be apart of a coprocessor 300arbitration scheme so that coprocessor 300 function may be efficientlysuspended in association with a first client so that the function may beoffered or delivered to a second client.

Embodiments of the present invention may be a system, a method, and/or acomputer program product. The computer program product may include acomputer readable storage medium (or media) having computer readableprogram instructions thereon for causing a processor to carry outaspects of the present invention. The computer readable storage mediumis a tangible device that can retain and store instructions for use byan instruction execution device. The computer readable storage mediummay be, for example, but is not limited to, an electronic storagedevice, a semiconductor storage device, or any suitable combination ofthe foregoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Java, Smalltalk, C++ or the like,and conventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions. These computer readable programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing thefunctions/acts specified in the flowchart and/or block diagram block orblocks. These computer readable program instructions may also be storedin a computer readable storage medium that can direct a computer, aprogrammable data processing apparatus, and/or other devices to functionin a particular manner, such that the computer readable storage mediumhaving instructions stored therein comprises an article of manufactureincluding instructions which implement aspects of the function/actspecified in the flowchart and/or block diagram block or blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowcharts and block diagrams in the Figures illustrate exemplaryarchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

It is understood in advance that although this disclosure includes adetailed description on cloud computing, implementation of the teachingsrecited herein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g., networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time. Measured service: cloud systemsautomatically control and optimize resource use by leveraging a meteringcapability at some level of abstraction appropriate to the type ofservice (e.g., storage, processing, bandwidth, and active useraccounts). Resource usage can be monitored, controlled, and reportedproviding transparency for both the provider and consumer of theutilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based email). Theconsumer does not manage or control the underlying cloud infrastructureincluding network, servers, operating systems, storage, or evenindividual application capabilities, with the possible exception oflimited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting for loadbalancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure comprising anetwork of interconnected nodes.

Referring now to FIG. 11, a schematic of an example of a cloud computingnode is shown. Cloud computing node 10 is only one example of a suitablecloud computing node and is not intended to suggest any limitation as tothe scope of use or functionality of embodiments of the inventiondescribed herein. Regardless, cloud computing node 10 is capable ofbeing implemented and/or performing any of the functionality set forthhereinabove.

In cloud computing node 10 there is a computer system/server 12, whichis operational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with computer system/server 12 include, but are notlimited to, personal computer systems, server computer systems, thinclients, thick clients, handheld or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 12 may be described in the general context ofcomputer system executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 12 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 11, computer system/server 12 in cloud computing node10 is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 12 may include, but are not limitedto, one or more processors or processing units 16, a system memory 28,and a bus 18 that couples various system components including systemmemory 28 to processor 16.

Bus 18 represents one or more of any of several types of bus structures,including a memory bus or data mover, a peripheral bus, an acceleratedgraphics port, and a processor or local bus using any of a variety ofbus architectures. By way of example, and not limitation, sucharchitectures include Industry Standard Architecture (ISA) bus, MicroChannel Architecture (MCA) bus, Enhanced ISA (EISA) bus, VideoElectronics Standards Association (VESA) local bus, and PeripheralComponent Interconnect (PCI) bus.

Computer system/server 12 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 12, and it includes both volatileand non-volatile media, removable and non-removable media.

System memory 28 can include computer system readable media in the formof volatile memory, such as random access memory (RAM) 30 and/or cachememory 32. Computer system/server 12 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 34 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 18 by one or more datamedia interfaces. As will be further depicted and described below,memory 28 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

Program/utility 40, having a set (at least one) of program modules 42,may be stored in memory 28 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 42 generally carry out the functions and/ormethodologies of embodiments of the invention as described herein.Computer system/server 12 may also communicate with one or more externaldevices 14 such as a keyboard, a pointing device, a display 24, etc.;one or more devices that enable a user to interact with computersystem/server 12; and/or any devices (e.g., network card, modem, etc.)that enable computer system/server 12 to communicate with one or moreother computing devices. Such communication can occur via Input/Output(I/O) interfaces 22. Still yet, computer system/server 12 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 20. As depicted, network adapter 20communicates with the other components of computer system/server 12 viabus 18. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 12. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Referring now to FIG. 12, illustrative cloud computing environment 50 isdepicted. As shown, cloud computing environment 50 comprises one or morecloud computing nodes 10 with which local computing devices used bycloud consumers, such as, for example, personal digital assistant (PDA)or cellular telephone 54A, desktop computer 54B, laptop computer 54C,and/or automobile computer system 54N may communicate. Nodes 10 maycommunicate with one another. They may be grouped (not shown) physicallyor virtually, in one or more networks, such as Private, Community,Public, or Hybrid clouds as described hereinabove, or a combinationthereof. This allows cloud computing environment 50 to offerinfrastructure, platforms and/or software as services for which a cloudconsumer does not need to maintain resources on a local computingdevice. It is understood that the types of computing devices 54A-N shownin FIG. 13 are intended to be illustrative only and that computing nodes10 and cloud computing environment 50 can communicate with any type ofcomputerized device over any type of network and/or network addressableconnection (e.g., using a web browser).

Referring now to FIG. 13, a set of functional abstraction layersprovided by cloud computing environment 50 (FIG. 12) is shown. It shouldbe understood in advance that the components, layers, and functionsshown in FIG. 14 are intended to be illustrative only and embodiments ofthe invention are not limited thereto. As depicted, the following layersand corresponding functions are provided:

Hardware and software layer 60 includes hardware and softwarecomponents. Examples of hardware components include mainframes, in oneexample IBM® zSeries® systems; RISC (Reduced Instruction Set Computer)architecture based servers, in one example IBM pSeries® systems; IBMxSeries® systems; IBM BladeCenter® systems; storage devices; networksand networking components. Examples of software components includenetwork application server software, in one example IBM WebSphere®application server software; and database software, in one example IBMDB2® database software. (IBM, zSeries, pSeries, xSeries, BladeCenter,WebSphere, and DB2 are trademarks of International Business MachinesCorporation registered in many jurisdictions worldwide).

Virtualization layer 62 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers;virtual storage; virtual networks, including virtual private networks;virtual applications and operating systems; and virtual clients.

In one example, management layer 64 may provide the functions describedbelow. Resource provisioning provides dynamic procurement of computingresources and other resources that are utilized to perform tasks withinthe cloud computing environment. Metering and Pricing provide costtracking as resources are utilized within the cloud computingenvironment, and billing or invoicing for consumption of theseresources. In one example, these resources may comprise applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal provides access to the cloud computing environment forconsumers and system administrators. Service level management providescloud computing resource allocation and management such that requiredservice levels are met. Service Level Agreement (SLA) planning andfulfillment provide pre-arrangement for, and procurement of, cloudcomputing resources for which a future requirement is anticipated inaccordance with an SLA.

Workloads layer 66 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation; software development and lifecycle management; virtualclassroom education delivery; data analytics processing; transactionprocessing; mobile desktop.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over those found in the marketplace, or to enable others ofordinary skill in the art to understand the embodiments disclosedherein.

1. A computer system comprising: a system memory shared by a processorand a coprocessor, the system memory comprising a shared portionaccessible by the coprocessor and the processor, and further comprisinga first application and a second application, the coprocessorcomprising: a compression and decompression engine accessed by the firstapplication being executed by the processor and a second applicationbeing executed by the processor, and a suspend and resume manager thatarbitrates first application and second application access to thecompression and decompression engine and saves coprocessor statemetadata describing the contents of the compression and decompressionengine to the system memory when suspending first application access andallowing second application access to the compression and decompressionengine.
 2. The computer system of claim 1, wherein the compression anddecompression engine comprises: a history first-in-first-out (FIFO)buffer and a hash table utilized to compress data received by thehistory FIFO buffer from the system memory.
 3. The computer system ofclaim 2, wherein upon suspending first application access to thecompression and decompression engine, the suspend and resume managerclears the contents of the history FIFO buffer and writes a target emptybit count (TEBC) to the system memory, the TEBC indicating the quantityof padding bits in the most recent compressed output from thecompression and decompression engine.
 4. The computer system of claim 3,wherein upon resuming first application access to the compression anddecompression engine, a system memory pointer the size of the historyFIFO buffer is rewound, data identified by the system memory pointer iswritten from the system memory to the history FIFO buffer, and thecontents of the hash table are recomputed.
 5. The computer system ofclaim 3, wherein upon resuming first application access to thecompression and decompression engine, newly resumed compressed outputfrom the compression and decompression engine is aligned with compressedoutput from the compression and decompression engine prior to suspend.6. The computer system of claim 1, wherein the processor, thecoprocessor, and the memory are connected by a memory bus.
 7. Thecomputer system of claim 1, wherein suspend and resume manager suspendsfirst application access to the compression and decompression engineupon the compression and decompression engine exceeding a dynamicsuspend threshold stored within the coprocessor.
 8. The computer systemof claim 1, wherein the compression and decompression engine comprises:a history first-in-first-out (FIFO) buffer and a decompression tableutilized to decompress compressed data received by the history FIFObuffer from the system memory.
 9. The computer system of claim 8,wherein upon suspending first application access to the compression anddecompression engine, the suspend and resume manager clears the contentsof the history FIFO buffer, clears the contents of the decompressiontable, and writes a source unprocessed bit count (SUBC) and writes asource final block type (SFBT) to system memory, the SUBC indicating theamount of compressed data ingested by the compression and decompressionengine that was not decompressed, and the SFBT indicating a type ofblock that was being decoded upon the suspending first applicationaccess to the compression and decompression engine.
 10. The computersystem of claim 9, wherein upon resuming first application access to thecompression and decompression engine, a system memory pointer is rewoundthe length according to the SUBC, data is identified by the systemmemory pointer is written from the system memory to the history FIFObuffer, and the contents of the decompression table are recomputed. 11.The computer system of claim 9, wherein upon resuming first applicationaccess to the compression and decompression engine, newly resumeddecompressed output from the compression and decompression engine isaligned with decompressed output from the compression and decompressionengine prior to suspend.
 12. The computer system of claim 1, wherein thefirst application is stored within a first partition of the systemmemory and the second application is stored within a second partition ofthe system memory. 13.-20. (canceled)